Friday, November 14th, 2014

Andreas Lyberatos
Dept. of Materials Science and Technology, University of Crete
Magnetic properties and switching dynamics of L1o-FePt nanoparticles: Application to heat assisted magnetic recording
Department of Physics Bldg., Voutes, 3rd floor Seminar Room

An upper limit to the areal density of magnetic storage in hard disk drives of 20 Tb/in2 is predicted [1] u sing a combination of heat assisted magnetic recording (HAMR) and a recording scheme that uses one FePt grain per bit. Currently areal densities are significantly smaller, ≈1Tb/in2, and progress is limited to less than 10%/year, as a result of significant challenges, some of which will be reviewed in this talk. The temperature dependence of the equilibrium magnetic properties of L1o-chemically ordered FePt nanoparticles in the size range 3-7 nm is of fundamental importance in modeling the HAMR process using the Landau-Lifshitz-Bloch equation. Recent progress is based on Monte Carlo simulations and application of finite size scaling theory. Nonequilibrium spin dynamics simulations based on an atomistic model of L1o-FePt are used to calculate the thermoremanence, optimize recording system parameters, calculate the recording time window and determine the thermomagnetic switching mechanism. Further challenges include multiscale modeling and development of a new cluster Monte Carlo algorithm.

[1] R.F.L. Evans, R.W. Chantrell, U. Nowak, A Lyberatos and H.J. Richter, APL 100, 102402 (2012)

See text.